The present disclosure relates to ceramic matrix composite components, and more particularly, to an internal cooling passage.
Gas turbine engines typically include a compressor section to pressurize airflow, a combustor section to burn a hydrocarbon fuel in the presence of the pressurized air, and a turbine section to extract energy from the resultant combustion gases. Gas path components, such as turbine blades, often include airfoil cooling that may be accomplished by external film cooling, internal air impingement, and forced convection, either separately, or in combination.
Ceramic matrix composite (CMC) components can endure high temperatures, but those temperatures may be below the gas path operational temperatures of some modern turbine engine stages. Internal convective cooling of CMC components may be primarily from impingement baffle like structures and film cooling from cooling passages. The cooling passages are either drilled using laser or Electron Discharge Machining (EDM). Laser passages are ideal for relatively short passages such as those at the leading edge of an airfoil, while EDM is ideal for long passages such as those at the trailing edge. EDM relies on a current supplied to an electrode which is discharged through a grounded part, however CMC material cannot carry current, and cannot use EDM. Machining cooling passages in the CMC component may result in cut fibers in the CMC material which may weaken the CMC component or expose a surface to environmental attacks.